1. Field of the Invention
The present invention relates to a switch type variable resistor, and more particularly to a dual connection switch type variable resistor.
2. Description of the Related Art
A conventional switch type variable resistor in accordance with the prior art comprises a control plate pivoted to the switch knob, an insulation fixing plate secured on the switch housing, a first terminal secured on one side of the insulation fixing plate, a second terminal secured on the other side of the insulation fixing plate, a conducting plate pivoted on the insulation fixing plate, and a positioning spring for positioning the conducting plate having a first end secured on the conducting plate and a second end secured on the insulation fixing plate. The positioning spring is used for positioning the conducting plate, so that the conducting plate is located at the opened or closed position. Thus, the number of the parts is increased, and the assembly work is more complicated and difficult, so that the switching action is not exact. In addition, if the mutual deflection of the resistors produces after assembly, it is necessary to dismantle the parts for adjustment, thereby causing inconvenience in use.
The primary objective of the present invention is to provide a switch type variable resistor comprising a rotation shaft, a bushing, a housing, a variable resistor portion, and a switch portion, wherein the switch portion includes:
a control plate, having a bottom edge formed with a lug;
a pair of electrode terminals, each having a tail end bent with a contact portion, one electrode terminal having an upper end pivoted with a rotary member and an annular connecting member by a rivet;
a rotary member, having a through hole for passage of the rivet, and formed with an insertion hole for insertion of the elastic connecting member;
an annular connecting member, made of a conducting metal, and having a through hole for passage of the rivet, the annular connecting member formed with a ring portion defining a penetration hole for passage of the rotation shaft, the penetration hole formed with a locking portion for locking the elastic connecting member, so that the annular connecting member may be rotated by the elastic connecting member, the ring portion provided with two contact guide portions corresponding to the positions of the contact portions of the two electrodes terminals;
an elastic connecting member having a first end inserted into the insertion hole of the rotary member, and a second end locked in the locking portion of the annular connecting member;
an insulating plate having a periphery formed with combination recesses, and a center defining a hole, the insulating plate having a front end riveted with the two electrode terminals, and a rear end defining a slide slot for limiting displacement of the elastic connecting member that protrudes from the locking portion of the annular connecting member;
a switch portion seat having a periphery formed with multiple combination pins, a center formed with a receiving hole, and having a front side formed with an opening for receiving each part of the switch portion;
wherein, the control plate is rotated by the rotation shaft, and the lug of the control plate is rested on the rotary member, so that the rotary member is rotated about the rivet, while the annular connecting member is rotated when the rotary member is rotated, so that the two contact guide portions of the annular connecting member is rotated to contact and conduct one of the two contact portions of the electrodes terminals on the insulating plate 53, thereby forming an opened or closed status.
Another objective of the present invention is to provide a switch type variable resistor, wherein the variable resistor portion disposed in a dual connection includes a pair of terminal seats each having variable resistor carbon film plates and terminals, a pair of contact plates, and a contact plate seat, each contact plate is rotated by the rotation shaft to contact the variable resistor carbon film plates of the terminal seat at different locations, thereby changing the resistance values, the contact plate seat consists of an upper seat and a lower seat, the upper seat has a periphery formed with adjusting teeth, while the housing is formed with adjusting windows corresponding to the positions of the adjusting teeth, thereby adjusting mutual deflection of the contact plates of the upper and lower seats and the variable resistor carbon film plates.
A further objective of the present invention is to provide a switch type variable resistor which has a shortened bulk.
A further objective of the present invention is to provide a switch type variable resistor whose switching action is exact and stable.
A further objective of the present invention is to provide a switch type variable resistor which has a long lifetime.
A further objective of the present invention is to provide a switch type variable resistor whose electrical contact is stable.
A further objective of the present invention is to provide a switch type variable resistor which can adjust the mutual deflection of resistors.
Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.